<正> My friend Jones is not a very practical person.Driving along a main road one dark night, he suddenlyhad a flat tyre. Even worse, he discovered that he didnot have a spare wheel in the back of his car. Joneswaved to passing cars and trucks, but not one of themstopped. Half an hour passed and he was almost indespair. At last he waved to a car just like his own.To his surprise, the car actually stopped and a well-